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6 marksTransformers

CSEC Physics · May/June 2009 · Paper 2 · Question 5(c)(ii)

A similar device includes a transformer for charging an MP3 player. The primary coil has 300 turns.

Given that the current in the primary winding is 10 mA, what power is transmitted to the secondary windings if the transformer is 77% efficient?

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Other parts of this question

  1. 5(a)Sketch the magnetic field associated with (i) a single bar magnet and (ii) between two strong bar magnets with their north poles facing, and in line with, each…[4 marks]
  2. 5(b)(i)How is the electromotive force (e.m.f.) generated in the stationary coil?[5 marks]
  3. 5(b)(ii)What ADDITIONAL component is needed to be able to charge the batteries?[5 marks]
  4. 5(b)(iii)At a reasonable cranking rate, the unit generates 6.2 V. Calculate the current in the circuit if the resistance is 310 Ω.[5 marks]
  5. 5(c)(i)How many turns are needed in the secondary winding if the voltage is stepped up from 6.2 V to 15.5 V?[6 marks]

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